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package org.apache.juneau.rest.annotation;

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;

import java.lang.annotation.*;

import org.apache.juneau.httppart.*;

/**
 * Annotation that can be applied to a parameter of a {@link RestMethod @RestMethod} annotated method to identify it as a HTTP
 * request header converted to a POJO.
 * 
 * <h5 class='section'>Example:</h5>
 * <p class='bcode'>
 * 	<ja>@RestMethod</ja>(name=<jsf>GET</jsf>)
 * 	<jk>public void</jk> doGet(RestRequest req, RestResponse res, <ja>@Header</ja>(<js>"ETag"</js>) UUID etag) {
 * 		...
 * 	}
 * </p>
 * 
 * <p>
 * This is functionally equivalent to the following code...
 * <p class='bcode'>
 * 	<ja>@RestMethod</ja>(name=<jsf>GET</jsf>)
 * 	<jk>public void</jk> doPostPerson(RestRequest req, RestResponse res) {
 * 		UUID etag = req.getHeader(UUID.<jk>class</jk>, "ETag");
 * 		...
 * 	}
 * </p>
 * 
 * <h5 class='section'>See Also:</h5>
 * <ul>
 * 	<li class='link'><a class="doclink" href="../../../../../overview-summary.html#juneau-rest-server.Header">Overview &gt; juneau-rest-server &gt; @Header</a>
 * </ul>
 */
@Documented
@Target(PARAMETER)
@Retention(RUNTIME)
@Inherited
public @interface Header {

	/**
	 * The default value for this header if it's not present in the request.
	 */
	String def() default "";

	/**
	 * HTTP header name.
	 */
	String name() default "";

	/**
	 * Specifies the {@link HttpPartParser} class used for parsing values from strings.
	 * 
	 * <p>
	 * The default value for this parser is inherited from the servlet/method which defaults to {@link UonPartParser}.
	 * <br>You can use {@link SimplePartParser} to parse POJOs that are directly convertible from <code>Strings</code>.
	 */
	Class<? extends HttpPartParser> parser() default HttpPartParser.Null.class;

	/**
	 * A synonym for {@link #name()}.
	 * 
	 * <p>
	 * Allows you to use shortened notation if you're only specifying the name.
	 */
	String value() default "";
}
